An Enhanced Joint Time-Scale and TDOA Estimator for Geolocation of Electromagnetic Transmitters

D.C. Smith (USA)


Geolocation, joint time-scale and TDOA estimation, sinc interpolation, Newton’s method, CAF, WBCAF


In this article we propose two enhancements to a known algorithm for joint estimation of time-scale (TS) and time difference-of-arrival (TDOA), and apply the enhanced algorithm to estimate parameters for geolocation of elec tromagnetic transmitters. The first enhancement extends the original method to accommodate complex-valued sig nals. The second enhancement reformulates the original algorithm to estimate differential receiver velocity rather than time-scale, which avoids precision problems encoun tered with the original algorithm at low SNR for very large sampled signal lengths. For geolocation, electromagnetic received signals have TS factors which are very close to unity, and performance figures for the original algorithm have been reported only for real-valued acoustic-type sig nals. Over a wide SNR range, when applied to simulated complex-valued electromagnetic signals, our enhanced algorithm produced TDOA estimates which are more than an order of magnitude more accurate than those attainable with a standard CAF grid search, and TS estimate errors which would require significantly more computation time to realize with a CAF-type search.

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